SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af7a926a30ae8a6b7d5c3924423375fbb729d431138b24040f831cde6c9d9c20' 
  AND token = 'yQ6Bb/zUbNHKmXpP2gWYJJgy+VhxznTBpT8/Pj1gUC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}